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RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: Mikeup

Great,Β* i sand the bottom with 2000 wet/dry black sandpaper with water and sand lenghtwise and do make it slick. I just dip paper in a cup of waterΒ*and sand and dry with a towel. Man it sure does look nice.Β*Β* Now if you look close at the last picture of bottom, it looks like its ready to burn water. Just got that LOOK>

What I do to make it slick is use Commercial waterbase floor finish in a satin or matte sheen. When this stuff dries, its like a sheet of ice. Its nice and slick, no sanding required.

Now that I have some finish on it, the colors really pop now. The cherry and and antique maple looks really sharp against the birch. This boat I kept all of the edges pretty sharp. The only taper is on the rake of the tub and sponsons. The trailing edges of the tub (transom) and sponsons all have sharp edges on the bottom. I canted the trailing edge of my sponsons on the outrigger I built, but I dont know if that has any hindrance on performance since the engine doesnt make enough power to get the heavy rigger on plane. I think that one might need a .61 that'll turn some better rpms than the .46 can do.

I tested all of the radio functions before final tear-down and everything is adjusted to work decent first run. I only worry if the engine is too heavy and sinks the back end too much. Once I get a few coats on it I'll float it in the bath tub and see where it sits. I'll probably post new pictures then.

RE: 3rd boat. flat deck 3-point hydro

Albeit a few minor servo adjustments, this thing is RTR. I only put 5 coats of clear polyurethane on it.. It could probably use more but since I dont even know if its going to run I didnt want to waste more time and add more weight. I didnt have a chance to weigh it, I'll do that tomorrow.

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: Mikeup

Pretty sharp!!!!!!!!

Thank you! I did a float test in my big jet tub and the back end sinks. I think if I hand launch it with a little throttle, it should stay up on top. If I get time over the weekend, I will shim the engine forward a little bit and see if that makes a difference. (I dont think it will change much) Hopefully it'll stay up and run out. I have my fingers crossed.

RE: 3rd boat. flat deck 3-point hydro

I hadn't posted the results of my initial test - FAIL. Through a twist of fate, I sanded the marks off on the engine plate of where I wanted to position the engine and forgot about the whole CG balance thing. Long story short - engine too far forward. nosedive. flip over cartwheel style. Made some adjustements to the engine stand, added styrofoam under the fuel tank shelf for a little extra floatation and the reslts so far are much better. She floats on her own, and the transom sits higher though still under water when sitting still. I tested the boat in the grass again with the engine shifted back and I'm much happier. Before, the back of the boat would lift off the ground when under power, now she scoots level and much easier I might add. I might try testing it out at the pond later today if I get time.

New pictures:
This is actually the rudder blade from the flatbottom that I modified a little bit. The solder joint between the rudder shaft and the blade was about 1 1/4" long, which made the boat "dance" side-to-side so I shortened the joint to 1/4"-3/8" instead. I already made this mod to the blade on the SICopy.
The rudder on the boat. (I am going to put a different rudder on this thing mounted higher when I can afford a speedmaster. rudder..) I used a nylon screw in the rudder bracket for a break-away.
Full Frontal
I need to find a tiny Minnesota Wild hockey sticker to put under the Minnesota cutout.. :lol:
I don't normally like stickers on my rides, but I couldn't help these two..
A sort-of bottom picture
Engine/Fuel Pump. (I added a return line because the regulator on the pump couldn't be dialed back enough to prevent the engine from flooding. Added benefit is the mixture doesnt change much from full tank to empty tank except for air bubbles at very low fuel levels. )

This engine is a little picky on fuel tank placement. I could probably get the engine to run fine without the pump and keep the tank below but I like the more consistent fuel mixture. I need to replace the O-rings on the Low speed needle valve before I re-test it, The low end and midrange was a little temperamental the other day.

RE: 3rd boat. flat deck 3-point hydro

tim...just studying your set up for a 3 point hydro...i am about to embark on this type of airboat myself...i have a tt60..what length and width would you suggest..looking at your hull size i was thinking of 18 x 24 ..keeping in mind the kit of selph is 29" long..i alsowish to make the engine mount slide back and forth so i can adjust the cg .. i think that is very importent i have a big swamp buggy and i cant adjust the cg without putting a heap of lead on it...it drags its rear end along puts the rudder mount under water and that slows it down to much...your thoughts much appreciated...bob

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: noisy

tim...just studying your set up for a 3 point hydro...i am about to embark on this type of airboat myself...i have a tt60..what length and width would you suggest..looking at your hull size i was thinking of 18 x 24 ..keeping in mind the kit of selph is 29'' long..i alsowish to make the engine mount slide back and forth so i can adjust the cg .. i think that is very importent i have a big swamp buggy and i cant adjust the cg without putting a heap of lead on it...it drags its rear end along puts the rudder mount under water and that slows it down to much...your thoughts much appreciated...bob

I am so sorry I never saw this post, Bob. Which SI3 is 29" long? The .25 size?

I have a BSB now as well, mine being extremely bow heavy. It needs to be torn down and rebuilt.

RE: 3rd boat. flat deck 3-point hydro

I decided to dust this thing off and tear it down to rebuild it so it will float, and maybe even run yet this year. Its been on the shelf while I run the snot out of my Kamikaze's.

Tore the skin off the bottom to make the center tub deeper, to aid in floatation. 1/32" plywood removed:
Balsa stringers added, making the transom 3/4" deeper than it was before, with a lighter taper to the bow.
Stringers glued on, and bulkhead spacers added, all balsa.
New Keel skin, made myself from 3/4" American Black Cherry. 4 strips 3/4" wide, 1 strip 15/16" wide. I used 4 small strips of cherry and epoxied them to the 5 strips to make one sheet out of it.
The skin strips are 1/32" thick and the 4 support strips are 1/16" thick

Waiting for the epoxy to cure, and I'll upload pictures of the skin on the hull.

RE: 3rd boat. flat deck 3-point hydro

tim...good to catch up with you...i am also well under way with a small 3 point...i am very happy at the moment..the only real change i made was i inverted my tt46pro and made my eng tower to slide back and forth so i could adjust the cg o the boat...i have a 31inch dumas swamp buggy..i had a 60tt on it and it went great..i put a tt90 on and it went very well but it did go with its nose in the air...that kit has no provision to move the eng tower to change the cg...i bought the 60 pland of ceph and hope to start the large size soon..but i wish to try the small one first..lookin for anty problems..i have a boating friend who is into hydro racing big time( not air boats) and he has been helping me...i will put up some pics soon as i get organized..i have been away for a whle ..now its time to get back into it....bob

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: noisy

tim...good to catch up with you...i am also well under way with a small 3 point...i am very happy at the moment..the only real change i made was i inverted my tt46pro and made my eng tower to slide back and forth so i could adjust the cg o the boat...i have a 31inch dumas swamp buggy..i had a 60tt on it and it went great..i put a tt90 on and it went very well but it did go with its nose in the air...that kit has no provision to move the eng tower to change the cg...i bought the 60 pland of ceph and hope to start the large size soon..but i wish to try the small one first..lookin for anty problems..i have a boating friend who is into hydro racing big time( not air boats) and he has been helping me...i will put up some pics soon as i get organized..i have been away for a whle ..now its time to get back into it....bob

Good to hear from you, Bob. Glad to hear you're building. My TT 46 is a great engine. I had mine inverted on another boat with a fuel pump but it didn't like that very much. It runs better without the pump and upright.

I'm going to test float my 3-pointer tonight. I'm really hoping I don't have to chop the engine stand down to save weight, but I will if needed. The stern sank some before, and in some of the update pics above, you can probably see why. If it floats on its own well, I'll pile weight on until the transom drops below the water line to see how big an engine I can run on it. Hoping the Enya 30ss works just right.

RE: 3rd boat. flat deck 3-point hydro

Some more progress on my failed 3-pointer... Cut the old engine stand off and made a new one to mount in its place. The new one is a couple ounces lighter and has a small amount of adjustability added to move the engine fore or aft a little if needed.

Bottom skin with 2 coats of resin and 2oz cloth, and polyurethane on top for a smooth and slick finish.
New engine stand, with Enya 30SS mounted up.

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: Ozpulse

Love the timber work mate, keep the pics. coming!Β*

Thank you kindly, Oz! I've been working on this thing here and there. Since it will float now, I'm swapping electronics from another boat to maybe test this thing out. I have the servos installed but I have to fashion a way to cram a 4-cell Rx pack in the cramped radio box. If I can get the radio box buttoned up and find my spare fuel tank, I will go to the pond for test runs. A re-maiden if you will. I need to find out if the engine will have enough thrust to pull it. The boat weighs 2 pounds 14 ounces RTR so I hope I get 3-4lbs of thrust minimum from the .30 engine. My .29 is 2000-3000rpm stronger on the same prop than the .30 but that's running a full tuned pipe. I don't think this hull will take to the long pipe because the hull is so small. (20"L x 14"W). I also have a mousse can I'm going to modify to use as a muffler that's half the weight of the .46 muffler I currently have on the .30.

RE: 3rd boat. flat deck 3-point hydro

No need to thank me mate, its not hard to admire genuine skill and care in craftsmanship thats required to make something that works and looks beautiful at the same time.
Ive always loved the old style timber boats etc. from back when paint wasnt needed as the mix of timbers used and their natural colours were what created the patterns, shapes and designs that made them so sought after (and expensive)
Gone are the days when things made from timber were works of art made with care by skilled hands. (DAMN YOU IKEA !)LOL
As for your RX battery problem, my LHS sells flat packs of the 4 rechargeable AA's (laying side by side)shrink wrapped and wired.
Would there be enough room to glue/DS tape/velcro one of these packs to the underside of your radio box lid??
Might be an option for you??

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: Ozpulse

No need to thank me mate, its not hard to admire genuine skill and care in craftsmanship thats required to make something that works and looks beautiful at the same time.
Ive always loved the old style timber boats etc. from back when paint wasnt needed as the mix of timbers used and their natural colours were what created the patterns, shapes and designs that made them so sought after (and expensive)
Gone are the days when things made from timber were works of art made with care by skilled hands. (DAMN YOU IKEA !)LOL
As for your RX battery problem, my LHS sells flat packs of the 4 rechargeable AA's (laying side by side)shrink wrapped and wired.
Would there be enough room to glue/DS tape/velcro one of these packs to the underside of your radio box lid??
Might be an option for you??

I hate IKEA stuff. Its cheaply made, of cheap materials. Worst part is, my wife loves the stuff. Whenever she goes there, she always wants me to come along.... and I can't stand it. Way too may people for me. Long gone are the days of quality built furniture for modest prices, that looks nice and is functional for 20+ years.

When I built this thing a couple years ago, I forgot how I set up the radio box since I pirated all of the electronics to put in one of my other boats. I figured out how I fit the pack in there, because I did get it in there at one time. I basically use the servos and their respective mounts to hold the Rx pack in place. I'll snap some photos of the radio box again.

Everything is tightened down now, control linkages are setup and adjusted, and I found the fuel tank. I just need to get the antenna tube installed and zip the radio box shut and its ready to get fueled up and carted to the pond. As soon as I get my first cup of coffee, I'll add some pictures. Im sure its gotta be like 10-11pm on your side of the planet, so you might not see them until tomorrow. Oh well.

RE: 3rd boat. flat deck 3-point hydro

Well, I got a chance to get out and test this boat a little bit. The verdict is: This one is not a total failure, but mostly. Its too narrow and a bit too short. It will ride on plane, albeit kinda low. It turns pretty well, but its too heavy and not big enough. For 5lbs, it should be 20% bigger for the same weight. I think I might be able to take it all apart, and re-use the control cables and just build a whole new boat. Target weight of the new one should be no more than 5lbs. Micro servos are going to be a must. I have plenty of 3/16" plywood, and 1/8" plywood. I'll make my own skin again for the bottom, and hopefully take 2 will work better.

I wont do anything further with this boat. I'm not heartbroken over it... It was a slap together type of thing, so I learned a few things and will make changes on the next round.

RE: 3rd boat. flat deck 3-point hydro

well those commente have me worried a little mine is about the same as yours..i keep trying to get some pics and comments up with sizes but it pourin here to..hope fully the next couple days...maybe i am better just buildin seph's full size machine and puttin my tt90 on and lettin it go at that..maybe they dont like to be reduced to much....bob

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: noisy

well those commente have me worried a little mine is about the same as yours..i keep trying to get some pics and comments up with sizes but it pourin here to..hope fully the next couple days...maybe i am better just buildin seph's full size machine and puttin my tt90 on and lettin it go at that..maybe they dont like to be reduced to much....bob

Well, the problems I see with my boat is its 2 1/2" shorter than the SI 20. From the pictures I've seen, is about the same width at 14" I think. Another problem I have is its just too darn heavy. While running it yesterday, it seemed to run straight okay - handling its own little wake well enough. The problem came in turning... The top deck isnt big enough, and in a turn, the lack of the extra width of the top deck allowed water to come over the top of the deck somewhat and add in the heavy weight of the thing, and it would roll a bit. I added some thin plastic chunks I had with me and some tape to add a "guard" of sorts to the rear part of the deck and this seemed to help quite a bit though it still rolled on me and flipped.

Here's what I mean:
This makeshift mod worked better as it seemed to turn better, but it still would drop in the water when slowing for a turn, and still rolled on me. So I'm drawing up a new hull. The new hull will have a larger top deck, and somehow I will make it lighter than its predecessor.

I know it took a lot of testing to get the SI3 to where it is today. The SI3 20 is "just" big enough for a .30-.35, though it needs a hand launch. A .25 is about right, but I dont have a .25. My Enya .30 is 9oz without muffler, and the TT muffler weighs in at 4oz and the muffler adapter is about 3/4 ounce. Add in the heavy metal geared servos and 4-cell alkaline battery, and too much other junk, and it comes in at 5lbs. I'm hoping to get this weight down to at least 3lbs, if not a little lighter. I think the weight is my biggest adversary with hull size being second.

RE: 3rd boat. flat deck 3-point hydro

So the re-rebuild has begun. Spent some time sanding and cutting some plywood to make a new hull. Old hull pictured above is 14"W x 19.5"L x 2"D. New hull is 16"W x 22"L x 2.25"D (rear of sponson) / 2"D (at transom). The engine mount is not going to be a one-piece unit like whats found on the real SI3's, Mine will be modular so it can be removed/replaced if needed. Top plate weighs a little over a pound, and the sponson parts are very light. The deck is 3/16" Birch 6-ply plywood, and the sponsons will be 1/8" 3-ply Maple (50+ year old carmelized maple ply is from an old door from my house). All bulkheads and support bracing inside the tub and sponsons will be 1/8" liteply. I'm tearing the old 3-pointer apart to use parts from it, namely the control cables.

RE: 3rd boat. flat deck 3-point hydro

Bought anther E-13 for Self-inflicted I'll put wooden sonsons on this one or cover with 1.32 ply. The last one has 1/ 32 on top for strenght and did the job. Foam safe sure gets expensive. I would like to use 5 minute thinned epoxy over ply but wonder if it will eat foam up. I kept all components case i had fun with the foam if i keep fingers away. Saftey swith is going in this one, Any ideas. Ponds here are pretty dry. Take care of your new future. i like the small er airboat, pretty slick in my books. TTYL!

RE: 3rd boat. flat deck 3-point hydro

ORIGINAL: Mikeup

Bought anther E-13 for Self-inflictedΒ* I'll put wooden sonsons on this one or cover with 1.32 ply. The last one has 1/ 32 on top for strenght and did the job. Foam safe sure gets expensive. I would like to use 5 minute thinned epoxy over ply but wonder if it will eat foam up. I kept all components case i had fun with the foam if i keep fingers away. Saftey swith is going in this one, Any ideas. Ponds here areΒ* pretty dry. Take care of your new future. i like the small er airboat, pretty slick in my books. TTYL!

I built the first one as an experiment and it did work after some tweaking, but the weight just didn't cut it. This one should work a little better. Keeping the weight down is imperitave. I'll get a few more parts cut today if I have time and I'll post more pictures as the rebuild progresses.

My band saw went down on me, so when I get it fixed I'll get your rudder done and sent off to you.